Abeta oligomers induce neuronal cell cycle events in Alzheimer's disease.
Neurons subject to degeneration in Alzheimer's disease (AD) exhibit evidence of re-entry into a mitotic cell cycle even before the development of substantial AD brain pathology. In efforts to identify the initiating factors underlying these cell cycle events (CCEs), we have characterized the appearance of the neuronal CCEs in the genomic-based R1.40 transgenic mouse model of AD. Notably, R1.40 mice exhibit neuronal CCEs in a reproducible temporal and spatial pattern that recapitulates the neuronal vulnerability seen in human AD. Neuronal CCEs first appear at 6 months in the frontal cortex layers II/III. This is 6-8 months before detectable amyloid beta (Abeta) deposition, suggesting that specific amyloid precursor protein (APP) processing products are responsible for the induction of neuronal CCEs. Furthermore, a reduction in the levels of Abeta (achieved by shifting the genetic background from C57BL/6 to the DBA/2 mouse strain) dramatically delays the appearance of neuronal CCEs. More significantly, elimination of beta-secretase activity blocks the appearance of CCEs, providing direct genetic evidence that the amyloidogenic processing of APP is required for the induction of CCEs. Finally, in vitro preparations of oligomeric, but not monomeric, Abeta induce DNA synthesis in dissociated cortical neurons, and this response is blocked by antioligomer specific antibodies. Together, our data suggest that low molecular weight aggregates of Abeta induce neuronal cell cycle re-entry in mouse models of Alzheimer's disease.
Varvel
Nicholas H
NH
Department of Neurosciences, NC30, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio 44195-0001, USA.
Bhaskar
Kiran
K
Patil
Anita R
AR
Pimplikar
Sanjay W
SW
Herrup
Karl
K
Lamb
Bruce T
BT
D000367:Age Factors; D000544:Alzheimer Disease / Q000235:genetics / Q000473:pathology*; D053829:Amyloid Precursor Protein Secretases / Q000172:deficiency; D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000172:deficiency; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000473:pathology; D004195:Disease Models, Animal; D004622:Embryo, Mammalian; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology*
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; C079240:Mtap2 protein, mouse; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse; D001973:Bromodeoxyuridine